What Is the Difference Between a Fixed Focal Length Lens and a Zoom Lens?

Understanding the difference between a fixed focal length lens and a zoom lens is significant in determining which lens may be best for certain types of photography. Selecting which type of lens is best for a situation depends on the subject matter and the photographer’s intentions. While perspective and composition are major considerations, things like weight, budget, practicality, and availability are just as important as artistic vision.

A careful examination of the uses of both types of lenses is one way to discern the distinctive differences for your photographic needs. Professional photographers find it advantageous to use both lenses for different types of photographic subjects and events.

Fixed Focal Length Lens

Also referred to as a "prime lens ," the fixed focal length lens (FFL) has a focal length that is not adjustable. Photographers are unable to zoom in and out on a particular subject when using a prime lens. Often used as a term opposite of zoom, prime lenses have only one focal length, with fewer moving parts and a simpler lens formula. A fixed focal length lens is less likely to produce images with chromatic aberrations (fringes of color along boundaries of dark and light parts of an image). FFL lenses come in all focal lengths, from a wide-angle lens to the longer telephoto lenses.

FFL Advantages

Simple Optics

The simpler optics of a fixed focal length lens means that it has a larger maximum aperture (smaller f-numbers). A lens aperture is the opening through which light travels; the larger the opening, the smaller the f-number. A larger aperture allows for photography in lower light and for photos with a shallow depth of field. Depth of field refers to the area of the photo that is sharply visible in comparison to the area that appears blurry. For example, in a shallow depth of field, the subject of the photo will appear sharp, but the background will appear blurred. In a photo with a deep depth of field, most or all of the photo will be in focus.

Fixed focal length lenses are faster because of the wider aperture. That is, a wider aperture allows the photographer to comfortably use higher shutter speeds to capture high-action photos in quick succession in lower light situations. In fact, a FFL lens is often the first choice for photographing dark, indoor, highly active situations such as indoor sports and live theatre. This lens allows for photographing indoors without using a flash.

The images produced with an FFL lens are very sharp and vivid. Colors tend to be more accurate because there are fewer glass elements between the subject and the image sensor.

Fewer glass elements also translate into a lighter weight. Should portability be an issue, prime lenses are much lighter than zoom lenses. A lighter lens is easier to carry and transport, particularly for shooting on location.

The focus ring on prime lenses is more sensitive. Although there may be times when a photographer uses autofocus, having the ability to manually focus with a super sensitive ring allows for as much latitude as possible for a sharp image. Dynamic focus of a prime lens allows for more variations and control.

Prime lenses are more budget-friendly option. Because there are fewer moving parts in a prime lens, they are priced lower than zoom lenses of the same caliber. There is often not a comparable zoom lens that can be found for the same amount of money that produces the same, high-quality, precise, vivid images as a prime lens.

FFL Disadvantages

The major disadvantage of a fixed focal length lens is that there is a single angle of view. Therefore, to get the composition that is most fitting for the subject matter, the photographer may need to get closer to the subject. Many times, this isn’t a problem, as a photographer will select the proper lens for a subject ahead of time with an understanding of the desired composition. However, if, for example, a photographer is using a macro prime lens to take close-ups of flowers, and then unexpectedly sees a bald eagle soaring above, there’s no way to capture the bird in flight without changing the lens. With a zoom lens, the photographer could go from petals to wildlife in less than a second.

Changing Lenses

Photographers who use prime lenses must change lenses each time they require a different focal length. Not only does lugging multiple lenses around become impractical when shooting outside of a studio, but each time a lens is changed, a photographer risks getting dust on the camera’s image sensor, as well as the lens itself.

Zoom Lens

A zoom lens comprises an assembly of various lens elements to allow for a range of focal lengths, from telephoto to wide angle. Photographers can take advantage of the varying focal lengths without having to switch the lens on their camera. A true zoom lens, also called a parfocal lens, is one that maintains focus even when the focal length changes. The varifocal lens is one that loses focus when zooming in and out.

The range of focal lengths is used to describe a zoom lens. A zoom lens that ranges from 100 mm to 400 mm. for example, ranges from the closest focal length of 100mm to the further focal length of 400mm. This range can also be described as 4:1 or 4x zoom, offering four times the zoom from the minimum to the maximum focal length. Professional photographic lenses can zoom as high as 100x. For beginning photographers, the telephoto zoom lens is one that will be most practical for a range of subjects. A lens that zooms from the "normal" focal length of 55 mm to the longer focal 200 mm is good place to

start.

Zoom Advantages

Various Focal Lengths

One zoom lens can do the work of multiple prime lenses to achieve the same range of focal lengths. Therefore, it is not necessary to bring along lenses that achieve other focal lengths when a zoom lens can accomplish the same task.

Cost Relative to Number of Lenses

Zoom lenses are typically priced higher than prime lenses. While this may seem like a disadvantage, one zoom lens can serve the same purpose as multiple prime lenses. Investing in a single zoom lens that covers a variety of focal lengths may prove to be more cost effective than purchasing multiple prime lenses to reach the same focal lengths.

Zoom lenses offer more flexibility and creative latitude, particularly when shooting active subjects. Photo journalists and photographers who shoot events such as weddings or sporting events prefer zoom lenses because they allow for quick changes of focal length to adjust for perspective and add variety to each shot within a matter of seconds.

In regards to proximity to a subject, no movement on the part of the photographer is required. Photographers can easily photograph their subjects from a variety of focal lengths without physically having to move. For photographic composition, moving to change angles is still necessary; however, it is not necessary to physically move close to a subject to hone in on details.

Zoom Disadvantages

Because there is a higher number of optical elements in a zoom lens, the camera is interpreting images based on varying focal lengths. As a result, images are not as crisp, clean, and vivid as they would be without the zoom adjustments. Beyond approximately a 3x zoom, images begin to be degraded, more so than they would be with a prime lens.

Zoom lenses are far more expensive than prime lenses. The various working parts of a zoom lens add to the increased cost. Often to get the same crisp, vivid images achieved with a prime lens, a zoom lens could cost more than $2,000. Again, however, the overall cost is relative to how many lenses a photographer would like to have and how he or she intends to use them. As such, it’s important to weigh the cost of one zoom against several prime.

Zoom lenses can be heavier than FFL lenses, making their portability for on-location shooting more challenging.

Which Type of Lens is Best?

When purchasing a camera lens, the first thing you have to evaluate is what you need the lens for. What are your subjects? What are your photographic goals? Photographers tend to be on the fence about choosing either the zoom lens over the fixed focal length lens. Professional photographers tend to use a range of prime and zoom lenses. For beginners, a flexible zoom might be the best option. However, if you have the budget, adding a few prime lenses to your collection will allow you to explore a greater variety of photographic techniques and achieve superior results.

Buying Zoom and Fixed Focal Lenses on eBay

Shopping for camera lenses in an online marketplace that offers selection with a range of types and brands is helpful to discern what types of lenses may be in your budget.

To locate camera lenses on eBay, begin in the Electronics section. Select Cameras and Photography. and then follow the link to Lenses and Filters. Once you are in this section of eBay, you can peruse all of the listings for lenses by selecting the Lenses link. Then, using the subcategory for Focal Length, you can specify Zoom or Fixed / Prime .

Alternately, to specifically locate FFL lenses using a keyword search, you can execute a general search under the words "fixed focal length lens " or "prime lens ." Unfortunately since the words are used interchangeably, you may need to search for FFL lenses under both descriptions. To search for zoom lenses, simply enter "zoom lens " into the eBay search engine.

If you are unclear if the lens is exactly what you are looking for based on the listed specifications, contact the seller directly. It is recommended to select top rated sellers with positive feedback from prior customers. The lens may require a test run before you make your final purchase, and in the instance that the lens is not the best fit for you or your camera, you may want to check with seller regarding a return policy.

Conclusion

When considering an FFL lens, photographers recommend the 55mm, particularly if the subject only requires one focal length. The 55 mm lens is considered a "normal" lens. In other words, it represents the normal view of the human eye. Selecting a zoom lens is more dependent on the subjects to be photographed. Photographing a subject at a great distance would require a telephoto zoom lens, while photographing landscapes that require more of the image to be included in the frame is best suited to a wide-angle zoom lens. While there are some lenses that could zoom from one aspect to the other very well without distortion, to purchase this type of lens would be very costly.

Although both types of lenses have their respective disadvantages, both types have significant advantages. Purchasing both types of lenses will allow more latitude in your photographic abilities and styles. Zoom lenses allow for more flexibility, particularly when photographing a dynamic subject. Fixed focal length lenses result in crisper, more vivid images that do not require flash, even when used indoors. If you have a tight budget or want to test each type of lens to develop your photographic skills, you may want to purchase a used or refurbished lens. An online marketplace such as eBay not only offers a range of listings by manufacturer, also listed by condition from new to refurbished.